1. Field of the Invention
This invention relates to a unit assembling error prevention structure for preventing a pitch discrepancy when assembling, for example, a battery connection plate, a unit to be assembled to a battery assembly of an electric vehicle.
2. Description of the Related Art
FIG. 5 shows a first example of a conventional unit assembling structure.
This structure fixes a unit of an elongated harness protector 50 to an outer wall 52 of a mating unit of a device 51 with small screws (fixing means) 53. The device 51 is installed, for example, on a vehicle and connected to a power source (not shown) through a wiring harness 54 inside the harness protector 50.
The harness protector 50 is made of synthetic resin into rectangular trough-like shape and is provided at both sides of its trough-like portion 55 with a plurality of brackets 56 disposed at equal pitches. The wiring harness 54 is received inside the trough-like portion 55 and fixed therein with a wound vinyl tape 57. Each bracket 56 is fixed to the outer wall 52 of the device 51 with the small screws 53.
The wiring harness 54 has a plurality of branch lines 58 which extend at substantially equal pitches from an intermediate portion of the harness protector 50, and a connector 59 at the tip end of each branch line 58 is fitted and connects to a connector (not shown) situated on the outer wall 52 of the device 51. The main line of the wiring harness 54 extends out at both ends of the harness protector 50 and is led inside the device 51 through apertures 60 formed in the outer wall 52.
With the above construction, however, when to install the harness protector 50 on the device outer wall 52, an operator, during fixation of the brackets 56 to the outer wall 52, may accidentally have the holes (not shown) of the brackets 56 misaligned or mismatched by one pitch in the longitudinal direction of the harness protector 50 with the threaded holes (not shown) of the outer wall 52. Consequently, a false connection is made between the branch line connectors 59 and the device 51 side connectors.
FIG. 6 shows a second example of a conventional unit assembling structure.
This structure fixes and connects units, i.e., a pair of elongated battery connection plates 62, 62xe2x80x2 to both ends of a mating unit of a battery assembly 63. The battery assembly 63 is installed on an electric vehicle inclusive of a hybrid car, and the battery connection plates 62, 62xe2x80x2 connect the batteries 65 (651, 652 . . . ) of the battery assembly 63 in series through a plurality of busbars 70 (701, 702 . . . ) thereof of conductive metal.
The batteries 65, each having a thin rectangular parallelepiped shape, are joined in a width direction thereof and fixed one another with a band 66. Each battery 65 has at its longitudinal ends a positive and negative electrodes 67 (671, 672 . . . ) or externally threaded terminals (fixing means) such that positive and negative electrodes 67 are arranged in an alternating manner at equal pitches P in the joining direction of the batteries 65.
Each battery connection plate 62, 62xe2x80x2 consists of a plate body 68 of synthetic resin which is substantially the same in length as the entire width of the battery assembly 63, a busbar 70 disposed in a plurality of rectangular grooves 69 formed on the plate body 68, and a cover 72 of synthetic resin rotatably provided via a hinge 71 to the plate body 68.
The busbars 70 are disconnected and independent from one another. One of the battery connection plates 62 is provided at both ends with a substantially square busbar 701 having one insertion hole 731 for the electrode 671 located at both left and right ends of the battery assembly 63. Each busbar 702 located at a longitudinally intermediate portion of the plate body 68 is rectangular in shape and has two insertion holes 732, 733 for electrodes 672, 673 of two batteries 652, 653. The busbar insertion holes 73 are provided at equal pitches, corresponding to the electrodes 67. The plate body 68 has relatively large circular holes 74 arranged at equal pitches at its rear side for receiving the electrodes 67. A plurality of busbars 70, each having two insertion holes 73, are disposed in the other battery connection plate 62xe2x80x2.
To describe with one of the battery connection plates 62 in FIG. 6, on assembling the battery connection plate 62 to the battery assembly 63, the positive electrode 67of the battery 651 at the left side end enters the insertion hole 731 of the left-side end busbar 701. Likewise, the negative electrode 672 of the second-from-left battery 652 enters one of the insertion holes 732 of the second-from-left busbar 702, and the positive electrode 673 of the third-from-left battery 653 enters the other insertion hole 733 of the second-from-left busbar 702, with the remaining electrodes 67 entering the insertion holes 73 of the remaining busbars 70. Each electrode 67 is tightened and connected to related busbars 70 with a nut 75. The electrodes 671 . . . at the left and right side ends connect through the busbars 701 . . . and not-shown plate terminals to a power source line (not shown).
On assembling the battery connection plate 62, a series circuit 76 as shown in FIG. 7 is constituted. Denoted 62 is the battery connection plate, 63 the battery assembly, 67 positive and negative electrodes, and 70 the busbars.
Reverting to FIG. 6, after each busbar 70 has been fastened and connected to the battery electrodes 67 with the nut 75, the cover 72 is closed to protect the busbars 70, electrodes 67, nuts 75 and the above plate terminals (not shown) in the plate body 68. The battery connection plate 62 thus also serves as a protector. The cover 72 has locking frames 77 engageable with locking projections 78 of the plate body 68 to lock the cover 72 in closed position.
With the above construction, however, there is worry that an operator, during assembling the battery connection plate 62 to the battery assembly 63, may connect the busbars 70 to the battery electrodes 67, with an inadvertent error made in aligning or matching the busbar insertion holes 73 with the battery electrodes 67 by one pitch. In this instance, as shown in FIG. 8, a closed circuit 79 as indicated by an arrow X is formed in the battery assembly 63, possibly causing a short circuit and sparks, and damages to batteries 65. In FIG. 8, denoted 62 is the battery connection plate, 67 the positive and negative electrodes, and 70 the busbars.
This invention has been accomplished to overcome the above drawbacks and an object of this invention is to provide a unit assembling error prevention structure which enables assembling a unit having fixing means at equal pitches such as a harness protector or a battery connection plate reliably to a mating unit such as a device or a battery assembly without a pitch discrepancy therebetween.
In order to attain the object, according to this invention, there is provided a unit assembling error prevention structure which comprises: a first unit; a second unit; a plurality of fixing means arranged at equal pitches, with which to assemble the first and second units together; two types of positioning frames, large and small, provided in an alternate manner on one of the first and second units; and a projection means provided on the other of the first and second units, which is capable of advancing into the large positioning frame, but abuts against the small positioning frame.
Preferably, the projection means comprises a pair of projections capable of advancing at opposite sides in the large positioning frame.
Preferably, the pair of projections each comprises walls intersecting at right angles.
Advantageously, the large positioning frame is replaced by an empty space.
Advantageously, the first unit comprises a battery connection plate, the second unit comprises a battery assembly, and the plurality of fixing means comprises electrodes of batteries constituting the battery assembly, the two types of positioning frames are provided on the battery connection plate, and the projection means is provided on every two of the batteries.
Preferably, the battery connection plate comprises a plurality of busbar receiving portions, and the two types of positioning frames, large and small, are provided on each of the busbar receiving portions.
Preferably, the plurality of busbar receiving portions are linked with resilient hinges to be movable relative to each other, and the positioning frames provided on each of the busbar receiving portions have a wall divided by a slit for each of the positioning frames and a wall opposite that wall, which is continuous for two or more of the positioning frames.
The above and other objects, features and advantages of this invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.